Drying of hydrazinium salt solutions for packaging



Jan. 21, 1964 P. MESSINA ETAL 3,118,805

DRYING 0F HYDRAZINIUM SALT SOLUTIONS FOR PACKAGING Filed July 12, 1961PHILIP MESSINA SU TIONG PHOA INVENTORS BY zwzw j;

AGENT United States Patent 3 118,805 DRYING 0F HYDRAZINIUM SALTSGLUTIONS FOR PACKAGING Phiiip Messina, Hanover, and Su Tiong Phoa,Baltimore,

Md, assignors to W. R. Grace 8; (30., New York, N.Y.,

a corporation of Connecticut Filed July 12, N61, Ser. No. 123,446 2Claims. (Cl. 159-47) This invention relates to the use of hydraziniumcompounds as textile softeners. In one specific aspect, this inventionrelates to the drying of hydrazinium compounds in preparation forpackaging as textile softeners.

Cationic textile softening agents are finding wide acceptance in bothmill and home laundry application. Over 8,000,000 pounds of cationicfinishing agents are used each year. It has recently been suggested thatselected hydrazinium salts, owing to their inherent chemical properties,would be effective textile softeners. And indeed, this has been found tobe the case. However, one of the big drawbacks is that most of theeffective compounds of this group exist normally in the liquid state,and are consequently somewhat cumbersome to use. And even moreimportant, the liquids are not easily adapted to the current popularpackaging methods wherein powdered laundering compounds are sealed inindividual water-soluble packages for easy, pre-measured addition towashing machines. The obvious solution to this problem is to dry thesecompounds, thereby rendering them suitable for use as a powder. But todate, this has not been successfully carried out in many compounds.

It is an object of our invention, therefore, to effect the drying ofhydraziniums and related compounds in such a way as to render themuseful as a powder.

It has been found that a simple but critical step must be added to theusual drying procedure where it is desired to pulverize the moredifiicul-tly dried compounds. The material is satisfactorily dried byheating in a vacuum dryer, after which it is subjected to a coolingperiod. Here, the dryer acts as a pulverizer, changing the large pastychunks ordinarily produced into a fine granular material. Thereafter,the material is reheated to dry it completely.

In accordance with our invention the compound to be dried is introducedinto a vacuum rotary dryer at suificiently high temperatures to insurethat said compound is in a fluid state. The jacket of the dryer ismaintained at a temperature such that this will remain the case. Solventis removed until the compound begins to foam or thicken. At this state,the temperature of the jacket is dropped below the freezing point of thecompound. We have found that generally, ordinary tap water, in the orderof 60 to 80 F. is low enough to bring about this change. At highertemperatures, the solids are waxy and do not tend to break up; oncooling, the solids become substantially hardened and break up onagitation. This reduced temperature is maintained for sufiicient timethat the agitating action of the rotary dryer effectively breaks up alllumps and gives a fine, granular material. The temperature of the dryeris then raised to a point at which the remaining volatiles areefficiently removed. The invention is more readily understood byconsidering in some detail and comparing two compounds,1,1-bis(perhydrotallow)-1-methyl hydrazinium chloride, and1,1-dimethyll-perhydrotallow hydrazinium chloride. Of these twocompounds, the former dries fairly readily, whereas the latter isordinarily more difiicultly dried. The reason for this lies in theprocesses by which the two compounds are made.

3,118,805 Patented Jan. 21, 1964 In both cases, the process involves twomain chemical reactions as shown below:

where R is a hydrogenated tallow (C -C or methyl radical and R is ahydrogenated tallow radical.

Reaction 1 shows the conversion of ammonia and chlorine to chlorarnine.Chloramine is then added to a tertiary amine to form the hydraziniur'nchlorides referred to above. Both of these reactions occursimultaneously in a solvent The molar ratio of ammonia to chlorine inthe reaction is maintained at about 5:1 at all time to prevent theformation of undesirable and hazardous nitrogen compounds. The reactionproceeds with both gases sparging from a twin fluid nozzle untilapproximately 200% of the theoretical chlorine required to form thehydrazinium chloride has been added. At this point the reaction isusually complete. The chlorine flow is discontinued and, after a fewminutes, so is the ammonia flow. Ammonium chloride is removed as asolid, after which the resulting filtrate is placed in a vacuum still.Here, solvent is evaporated from the solution at a liquid temperature ofabout 140 F. and an absolute pressure of 15 inches of mercury. It isdesirable to operate at low temperature to avoid discoloration of thefinal product. Evaporation to about 70% solids level, at which point thematerial is still fluid, is complete in about 6 to 10 hours, and therecovered solvent is recycled.

The problem arises in the final drying step. In some instances, thedrying is not difficult. For purposes of comparison, the drying of1,1-bis(perhydrotallow)-1- methyl hydrazinium chloride is described astypical of the procedure where no particular difiiculties areencountered. The concentrated solvent at temperatures of 130- 140 F.containing approximately 70% by weight of the hydrazinium chloride ispumped or sucked into a rotary vacuum dryer by maintaining a slightvacuum on the dryer. Liquid is drawn into the dryer until a chargesomewhat greater than 50% of the total volume is achieved. During thischarging period the jacket is maintained relatively cool, usually belowF. At the completion of charging, the vacuum is gradually increased tothe maximum capacity of the vacuum system. The material is agitatedduring this period, but no external heat is applied to the jacket.Within 1 or 2 hours the liquid within the dryer will solidify togranules or chunks which eventually become a fairly smooth flowingpowder. When solidification is complete, drying is continued bymaintaining a temperature of about F. in the jacket and maximum vacuuminside the unit. Final volatiles are below 2% However,1,l-dimethyl-l-perhydrotallow hydrazinium chloride does not dry asreadily as the compound described above, and hence production of it isseriously affected. We have modified the drying procedure in the mannerdescribed as follows to achieve rapid, thorough drying.

Referring to the accompanying drawing, the concentrated liquid is drawninto a vacuum rotary dryer 1, driven by a motor 2 at -150 F. byemploying the vacuum system. The jacket 3 is again maintained at about100 F. or lower. The dryer is charged in this instance to somewhat lessthan 50% of the total volume and full vacuum is applied until thematerial forms a heavy pasty mass. In the case of this compound, ascompared with the one described previously, the material does not gorapidly to a fine granular powder but does solidify in large pastychunks. When the pasty mass is obtained the jacket temperature isincreased, usually to about 165 F., and held there for about one hourwhile the entire mass is agitated. After the one hour period, cold wateris introduced into the jacket 3 While still agitating the mass. Therotary vacuum dryer at this point really acts like a large pulverizerand the chunks are slowly ground into a fine granular material. Oncethis point has been achieved, heat is applied to the jacket 3 again to amaximum temperature or about 120 F. and the drying is continued tocompletion. The solvent evaporated from the solids is recovered fromcondenser 4. Final volatiles are below 2% The method set out above maybe applied to other difficultly dried long-chain hydrazinium salts. Aswell, quaternary ammonium compounds already on the market as textilesofteners but none in the dried form, could be reduced to drydispersible powders by the same general technique.

We claim:

1. A method of reducing diflicultly dried hydrazinium salts todispersible powders comprising drawing a concentrated solution of saidhydrazinium salt into a vacuum rotary dryer at a temperaturesufiiciently high to insure that the compound is in a fluid state,equipping said dryer with a water jacket having means for the ingressand egress of water and serving as a heat exchanger, charging said dryerto just under 50% of the total volume, applying vacuum to said dryeruntil said compound exhibits signs of solidification, maintaining saidvacuum and increasing the temperature of said jacket to a temperaturesufiiciently high to evaporate solvent efficiently maintaining saidtemperature until said compound begins to foam and thickensubstantially, introducing water at a temperature below the freezingpoint of said compound into said jacket, continuing the agitation untilthe thickened mass is a fine granular solid, and reapplying heat to saidjacket to completely dry said compound.

2. A method of reducing 1,l-dimethyl-l-perhydrotallow hydraziniumchloride to a dispersible powder comprising drawing a concentratedsolution of said compound into a vacuum rotary dryer at 130 to 150 F.,equipping said dryer with a Water jacket having means for the ingressand egress of water and serving as a heat exchanger maintaining saidjacket of said dryer at about 100 F., charging said dryer to just underof the total volume, applying vacuum to said dryer until said compoundforms a heavy mass, increasing the temperature of said jacket to about165 F., agitating said mass at said temperature until said compoundbegins to foam and thicken, introducing water at a temperature of about-80" F. to said jacket with continued agitation of said mass until saidmass is converted to a fine, granular material, and increasing thetemperature of said jacket to about F. to dry said compound tocompletion.

References Cited in the file of this patent UNITED STATES PATENTS668,159 Campbell Feb. 19, 1901 1,297,496 Rogers Mar. 18, 1919 1,831,049Treschow Nov. 10, 1931 2,087,788 Thal July 20, 1937 2,716,052 FelgerAug. 23, 1955 FOREIGN PATENTS 818,431 Great Britain Aug. 19, 1959

1. A METHOD OF REDUCING DIFFICULTY DRIED HYDRAZINIUM SALTS TO DISPERSIBLE POWDERS COMPRISING DRAWING A CONCENTERED SOLUTION OF SAID HYDRAZINIUM SALT INTO A VACUUM ROTARY DRYER AT A TEMPERATURE SUFICIENTLY HIGH TO INSURE THAT THE COMPOUND IS IN A FLUID STATE, EQUIPPING SAID DRYER WITH A WATER JACKET HAVING MEANS FOR THE INGRESS AND EGRESS OF WATER AND SERVING AS A HEAT EXCHANGER, CHARGING SAID DRYER TO JUST UNDER 50% OF THE TOTAL VOLUME, APPLYING VACUUM TO SAID DRYER UNTIL SAID COMPOUND EXHIBITS SIGNS OF SOLIDIFICATION, MAINTAINING AID VACUUM AND INCREASING THE TEMPERATURE OF SAID JACKET TO A TEMPERATURE SUFFICIENTLY HIGH TO EVAPORATE SOLVENT EFFICIENTLY MAINTAINING SAID TEMPERATURE UNTIL SAID COMPOUND BEGINS TO FOAM AND THICKEN SUBSTANTIALLY, INTRODUCING WATER AT A TEMPERATURE BELOW THE FREEZING POINT OF SAID COMPOUND INTO SAID JACKET, CONTINUING THE AGITATION UNTIL THE THICKENED MASS IS A FINE GRANULAR SOLID, AND REAPPLYING HEAT TO SAID JACKET TO COMPLETELY DRY SAID COMPOUND. 